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수술후 잔위에서 Helicobacter pylori의 분포와 조직학적 위염 정도의 상관성
서정인 ( J. I. Seo ),박광하 ( K. H. Park ),김현수 ( H. S. Kim ),박동훈 ( D. H. Park ),김문영 ( M. Y. Kim ),백순구 ( S. K. Baik ),이동기 ( D. K. Lee ),권상옥 ( S. O. Kwon ) 대한소화기학회 2002 대한소화기학회 춘계학술대회 Vol.2002 No.-
<목적> 위부분절제술 후 약 60-100%에서 알카리 역류성 위염이 발생하며 주로 문합부에 발생되고 분문부에는 발생 빈도가 적은 것으로 알려져 있다. 이러한 잔위염의 발생에는 담즙의 역류가 관여하여 Helicobacter pylori의 역할에 대하여는 논란이 있다. 본 연구는 위부분절제술 후 잔위에서 H. pylori의 분포와 감염 여부에 따른 위염 정도의 상관성을 알아보고자 하였다. <방법> 2001년 2월부터 8월까지 원주기독병원 소화기내과에 내원한
저속 비행체 공력해석을 위한 상용 및 오픈 소스 CFD 코드 비교
박동훈(D.H. Park),김철완(C.W. Kim),이융교(Y.G. Lee) 한국전산유체공학회 2016 한국전산유체공학회지 Vol.21 No.2
The comparison of two commercial codes(FLUENT and STAR-CCM+) and an open-source code(OpenFOAM) are carried out for the aerodynamic analysis of flight vehicles at low speeds. Tailless blended-wing-body UCAV, main wing and propeller of HALE UAV(EAV-3) are chosen as geometries for the investigation. Using the same mesh, incompressible flow simulations are carried out and the results from three different codes are compared. In the linear region, the maximum difference of lift and drag coefficients of UCAV are found to be less than 2% and 5 counts, respectively and shows good agreement with wind tunnel test data. In a stall region, however, the reliability of RANS simulation is found to become poor and the uncertainty according to code also increases. The effect of turbulence models and meshes generated from different tools are also examined. The transition model yields better results in terms of drag which are much closer to the test data. The pitching moment is confirmed to be sensitive to the existence and the location of transition. For the case of EAV-3 wing, the difference of results with k-ω SST model is increased when Reynolds number becomes low. The results for the propeller show good agreement within 1% difference of thrust. The reliability and uncertainty of three codes is found to be reasonable for the purpose of engineering use. However, the physical validity and reliability of results seem to be carefully examined when k-ω SST model is used for aerodynamic simulation at low speeds or low Reynolds number conditions.
박동훈(D.H. Park),김철완(C.W. Kim) 한국전산유체공학회 2014 한국전산유체공학회 학술대회논문집 Vol.2014 No.11
Performance analysis of HALE UAV propeller is carried out for comparison and analyzing the results with experimental data from wind tunnel test. Measuring device, supporting column, and test section wall of wind tunnel are chosen as major elements of interest which can yield change of measured performance in the experiment. Effect of each element is examined by comparison with result obtained by considering propeller only. The blockage effect produced by measuring device and support column is found to contribute for a small amount of increase of thrust, torque, and efficiency. Wall effect due to tunnel wall also has influence on performance increase, however, its effectiveness is smaller than the device and column. Overall effects from all elements shows approximately 1.81% and 0.68% increase of thrust and torque, respectively. Performance curves obtained by taking into account all the elements shows closer agreement with experimental data.